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Oracle Table Indexes: 1 vs many columns


Oracle Table Indexes: 1 vs many columns

By : Rich G
Date : November 17 2020, 11:58 AM
will help you Yes, Oracle will use a Index which contains more columns the same way as an index with less columns (as long as you use the leftmost columns).
Thats true for some joins as well as where predicates or FK checking.
code :


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SQL/Oracle: when indexes on multiple columns can be used

SQL/Oracle: when indexes on multiple columns can be used


By : James Chapman
Date : March 29 2020, 07:55 AM
hope this fix your issue There are actually three index-based access methods that Oracle can use when a predicate is placed on a non-leading column of an index.
i) Index skip-scan: http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/optimops.htm#PFGRF10105
Add Indexes to columns in remote table - Oracle

Add Indexes to columns in remote table - Oracle


By : Harry
Date : March 29 2020, 07:55 AM
around this issue You could use DBMS_JOB or DBMS_SCHEDULER packages on the remote database to schedule a job, executing DDL.
But consider this, if Oracle throws an exception for DDL over databse links, there must be a good reason for it, right? You don't want anyone messing with your schema remotely over a database link. So instead, talk to the remote DBA and try to figure out solutions with him/her.
Oracle 2 Indexes on same columns but different order

Oracle 2 Indexes on same columns but different order


By : Hashar Nawaz
Date : March 29 2020, 07:55 AM
help you fix your problem Indexes are tied to the fields they're indexing, in the order they're being defined in the index. As long as you use the fields in the index, in their left->right order, then index is useable for your query. If you're skipping fields, then the index cannot be used. e.g. given the following index:
code :
CREATE INDEX ind1 ON foo (bar, baz, qux)
WHERE bar=1
WHERE bar=1 AND baz=2
WHERE baz=2 AND bar=1  <--same as before
WHERE bar=1 AND baz=2 AND qux=3
WHERE baz=2  <-- 'bar' not being used
WHERE baz=2 AND qux=3  <-- 'bar' again not being used
WHERE bar=1 AND qux=3  <-- the index can be partially used to find `bar`, but not qux.
(STORE_ID, DIST_ID)
(DIST_ID)
in Oracle, how to select unique together indexes for table along with affected columns

in Oracle, how to select unique together indexes for table along with affected columns


By : Javier Coronel Barac
Date : March 29 2020, 07:55 AM
Hope that helps If I execute this query: , Try like this,
code :
SELECT i.index_name,  
       c.column_position,  
       c.column_name,  
       i.uniqueness
  FROM sys.all_indexes i, 
       sys.all_ind_columns c  
 WHERE i.table_name  = 'MY_TABLE'  
   AND i.owner       = 'ME'  
   AND i.uniqueness  = 'UNIQUE'
   AND i.index_name  = c.index_name  
   AND i.table_owner = c.table_owner  
   AND i.table_name  = c.table_name  
   AND i.owner       = c.index_owner
   AND c.index_name IN (SELECT index_name FROM sys.all_ind_columns WHERE column_position = 2);
Oracle 12c - how to create a new table form existing table with all data, partitions and indexes like in first table?

Oracle 12c - how to create a new table form existing table with all data, partitions and indexes like in first table?


By : user7440198
Date : March 29 2020, 07:55 AM
With these it helps Table t1 is partitioned and has data. , Use dbms_metadata to get the whole structure.
code :
SELECT dbms_metadata.get_ddl( 'TABLE', 'SOURCE_TABLE_NAME' ) FROM DUAL;
SELECT dbms_metadata.get_ddl( 'TABLE', 'SOURCE_TABLE_NAME', 'SOURCE_SCHEMA_NAME' ) FROM DUAL;
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